When Justin Gatlin and then Tyson Gay crossed the finish line in the final of the 100 metres on day three of the US Olympic trials, it was a moment as familiar as it was remarkable. They are, of course, two of the fastest men in the world. They are icons of US track and field. But not long ago both seemed unlikely to qualify for the 2012 London-bound team.

Gatlin – an Olympic gold medallist and once US track's favourite son – was exiled in disgrace, banned four years away from the sport he loved to serve a suspension for steroid use. At the weekend he ran a 100m personal best of 9.80sec. "I heard a lot of words this season: 'Redemption, my journey'," Gatlin said after his victory. "I just focused on sticking to what I know and being a fast runner."

And Gay, who out-bolted the Jamaican Usain Bolt five years ago to win a world title, has since stumbled, endangered by injuries – including hip surgery that rendered him unable to even jog as recently as March. Finishing a surprise third was Ryan Bailey, who owes his trip to London in part to his injured team-mate Walter Dix, who hobbled to last place on an injured left hamstring.

It was comeback day in the men's 400m race, too. In front of the record crowd at the University of Oregon's Hayward Field, LaShawn Merritt finished his race in 44.12, the best in the world this season, for a chance to defend the gold next month. The reigning 400m Olympic champion, Merritt served a 21-month suspension after testing positive for steroid derivatives called DHEA and pregnenolone in 2009-10.

"This won't be my first rodeo, so I'm confident," he said after the race. Qualifying again, he said, "is a birthday present to myself".

But the truly heroic victory in that race on Sunday belonged to Bryshon Nellum, a senior at the University of Southern California, who finished third behind Merritt and Tony McQuay. Nellum, a track star since high school, was shot three times in the legs while leaving a Halloween party where he was misidentified as a rival gang member. His most recent surgery was just last year. "It's been a long journey for me," he said. "I finally had a healthy season. It's a blessing to be able to compete out here."

The women's 100m was not as clear cut as the men's race due to an unprecedented third-place tie. USA Track & Field has yet to name the third runner to make the team. As expected, the world champion Carmelita Jeter pushed past Tianna Madison to win. But Allyson Felix finished level with her team-mate Jeneba Tarmoh for third in 11.068.

Track officials said there was no protocol in place for a third-place tie in an Olympic trial and that, surprisingly, such an outcome had no precedent. It was not until the end of the next day that the organisation settled on new procedures for a tie. The tied athletes must independently choose either a) a coin toss or b) a runoff – or decline to choose either one.

If either one chooses a runoff, there will be a runoff. If both refuse to choose a method, there will be a coin toss. Another option is that one of the athletes could decline his or her position and go to London as an alternate.

There is no deadline for the decision, but the US team must be chosen by the end of competition on Sunday. Bobby Kersee, who coaches both athletes, has expressed a strong preference to let Felix and Tarmoh run the 200m, which concludes Saturday, before making a decision.

The weekend in Eugene – dubbed Track Town USA for its running tradition – was also packed with firsts and records. Most notable was the mark set by Ashton Eaton, 24, the youngest of a celebrated trio of decathletes that includes Brian Clay and Trey Hardee. He surpassed them both on the second day to win the decathlon and set a world record of 9,039 points in front of his home team crowd.

Clay, the Olympic champion, shocked the crowd when he hit the final hurdle in his 110m hurdles heat and found himself initially disqualified. Although his points were later reinstated, by then a distracted Clay had failed to register a mark in the discus and was already losing ground on the leaders after day one. Lacking the Olympic 'A' standard, he was no longer in contention for one of the three places in London.